This invention relates to a blade or tool clamp for a reciprocating blade or tool such as a sabre saw blade; and more particularly, to a blade clamp which will accept and grip an unnotched or unapertured blade upon simple insertion thereof, hold the blade firmly in use, and readily release the blade upon exertion of slight pressure on a release device.
In the prior art there have been many efforts to insure that a tool such as sabre saw blade, which undergoes endwise reciprocation and is, therefore, subject to extreme dislodging force, will remain in the inserted position. For example, in U.S. Pat. No. 3,781,025, of Di Angelo, two set screws are used on opposite sides of the chuck and longitudinally spaced from each other in order to force a slight "S" bend in the saw blade in order to firmly retain the same against the reciprocating forces tending to dislodge the saw blade. In this patent, it is noted that plural sets of set screws contacting the blade at right angles have also been used but found to be not entirely satisfactory.
Attempts to retain the sabre saw blade have utilized many forms of edge cut outs in the shank of the blade, which cut outs are engaged by cams or rollers in the inserted position of the blade to retain the same firmly. An example of this type of construction might be seen in the U.S. Pat. No. 4,299,402, of Hoffman.
In the U.S. Pat. No. 3,583,716 of Daniel, Jr., a quick attachment of a saw blade to a saw bar is obtained by utilizing a saw blade having a shank with an aperture therethrough, which aperture receives an inwardly cammed ball bearing to lock the saw blade to the saw bar during endwise reciprocation of the same. This assembly is readily effected by rotating the cam to allow the ball bearing to withdraw from the aperture in the saw blade shank, whereupon the saw blade may be removed.
However, these prior art devices either place an excessive strain upon the saw blade by local deformation of the same; or by requiring a particular blade aperture or edge cut out, restrict each chuck to use only with its own particular saw blade arrangement. It is apparent that what is required is a sabre saw blade clamp which is capable of accommodating any arrangement of sabre saw blade shank so as to avoid excessive strain thereon or the necessity for any particular configuration of edge cut out or aperture. Ideally, it should be accomplished as economically and as simply as possible.